#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

int factorial (int num);

int main() {

    int n;
    printf("Enter number to calculate factorial: ");
    scanf("%d",&n);
    printf("\n%d",factorial(n));

    return 0;
}

int factorial (int num) {

    if ( num <= 1 ) return 1;
    else return num * factorial ( num - 1 );

}